The Corps’ Mississippi Valley New Orleans (MVN) began opened 10 bays on the Bonnet Carré Spillway on Friday, April 3, 2020. The MVN planned to open 20 bays on the first day in order to keep the maximum flow at New Orleans at or below the target flow of 1.25 million cubic feet per second. However, based on lower forecast flows only 10 bays needed to opened on the first day diverting about 16,000 cubic feet per second from the Mississippi River and into Lake Pontchartrain via the floodway.
The Bonnet Carre´ Spillway is a flood control structure extending from Mile 128.8 Above Head of Passes to Mile 127.3 Above Head of Passes that is designed to pass flood water from the Mississippi River into Lake Pontchartrain to prevent flooding below the Spillway. The flood control structure has total of 350 bays at this point only 10 have been opened.
The Mississippi River forecast shows a gradual increase in flow up to the dates of the projected crest on April 11th and April 12th. Current flow rates in the river have been less than originally forecasted. The MVN did not plan to open any additional bays over the weekend. As of today’s forecast, the maximum predicted flow through our structure will be approximately 90,000 cfs for this opening, with an overall duration of 3-4 weeks.
BONNET CARRÉ SPILLWAY OPERATION 2020
|DATE||CARROLTON GAUGE (NEW ORLEANS)||NUMBER OF BAYS OPENED||NUMBER OF BAYS CLOSED||NUMBER OF BAYSREMAINING OPEN||SPILLWAY DISCHARGE CUBIC FEET PER SECOND (cfs)|
|4/3/20||16.30 feet||10||0||10||16,000 cfs|
|4/4/20||16.38 feet||0||0||10||19,000 cfs|
|4/5/20||16.60 feet||0||0||10||21,000 cfs|
A forecast update provided by our colleagues from the National Oceanic and Atmospheric Administration’s (NOAA) Lower Mississippi River Forecast Center is attached, highlights from this update specific to the New Orleans are reproduced below:
“The Bonnet Carré Floodway will be operated today to help reduce flow at New Orleans, LA. This will cause New Orleans, LA and Reserve, LA to crest before upstream locations. New Orleans, LA will be regulated to the 17.0 ft flood stage. This will be the first time that the floodway has been operated for 3 years in a row. The floodway has been operated for 4 of the last 5 years.
The 16 day future rainfall guidance is showing a secondary crest on the lower Ohio River for late April. This crest would be several feel lower than the current crest and it would only slow recessions on the lower Mississippi River for early May.”
The Bonnet Carré Anchorage was closed by the U.S. Coast Guard at 6:00 a.m. this morning (April 3, 2020), vessels shall not enter the anchorage or the area extending 600 feet into the river from the Bonnet Carré Spillway, between MM 127 and MM 129 and the shoreline of Lake Pontchartrain.